I have to say that T-Spline is the best converter. I us eit to convert only base shapes. Now I'm working on this helicopter I made it in Nvil (3 hoours work) and now convert it to MOI.
As you can see cage is very tight, but T-Spline treat it very well! I use this tight cage becouse in Nvil as you can see I used Creas and to save these edges I have to make tight cage.

Looks liek I take the best from Poly and Nurbs. The fastest workflow made organic base shape in poly and then finish it in MOI.